Tracing device



w. BEGEROW TRACNG DEVICE May 3, 1949.

2 Sheets-Sheet 1 Filed June 9. y1945 INVENTOR. 1f/5 @fw from w. 'BEG ERow TRACING DEVICE May 3; 1949.

Filed June 9, 1945 @M fm;

. Maf/ms:

Patented May 3, 19.49

TRACING DEVICE Walter Begerow, Wood-Ridge, N. J., assignor to Air Reduction Company, Incorporated, a corporation of New York f' Application June 9, 1945, Serial No. 598,544

6 Claims.

This invention relates to tracing devices for guiding the course of an instrumentality, such as a cutting or welding torch, in accordance with a drawing or pattern traced by the device. Tracing devices of this kind are commonly used on universal cutting or welding machines such as those of the folding pantograph type in which a gas cutting or welding torch is mounted on one part of a pantograph structure, such as the front bar of a folding parallelogram frame, and the tracing device is mounted on another part so that the torch is capable of universal movement in a plane and so that when the tracing device is caused to follow the outline of the drawing or pattern the torch will be guided accordingly.

One type of tracing device for use in this way comprises a power-driven traction wheel that rolls on the surface containing the drawing or pattern. The wheel is guided along the outline of the drawing or pattern and is steered about a vertical axis that passes through the point of traction. Power is supplied to the traction wheel from an electric motor through a vertical drive shaft and worm coaxial with the axis about which the traction wheel is turned when steering.

The traction wheel is usually steered by hand to cause it to follow the outline of the drawing or pattern. Recently, however, an electronic tracing device has been proposedl in which the traction wheel is automatically steered and caused to follow the outline of the drawing or pattern. The tracing device has means for projecting a beam of light on the line forming the drawing and the light is reflected into a photoelectric cell. The variation in the amount of light received by the photo-electric cell if the traction wheel deviates too far from the line of the drawing causes the steering mechanism to steer the traction wheel back toward the line. Most oi the additional mechanism required to produce the automatic steering of the traction wheel is located Within a housing carried by the tracing device. To shield the portion of the drawing that is influencing the photo-electric cell from as much light as possible except that which is purposely projected onto it through the bottom of the housing, the bottom of the housing is made rather large in area and is positioned fairly close to the surface containing the drawing or pattern. This so obscures the traction wheel that its orientation, i. e. the direction in which it is headed, cannot be readily observed by the operator. This is a disadvantage since the traction wheel should of course be adjusted before the tracing operation is started so that it is' (Cl. Z50-41.5

oriented or headed substantially in the direction of the portion of the drawing on which it is resting at the time, otherwise the tracing device might get out of control of the automatic steering mechanism at the very beginning of the tracing operation.

According to the present invention a tracing device of the above described type, in which the traction wheel is so obscured that its orientation cannot be readily observed by the operator, has an indicator element at a location where it may be readily seen by the operator which will indicate to him the orientation of the traction wheel at all times.

A tracing device embodying the invention is illustrated in the accompanying drawing in which:

Fig. 1 is a side elevation, partly in vertical section, of the tracing device;

Fig. 2 is a front elevation thereof; and

Fig. 3 is a vertical section of that portion of the tracing device where the indicator element is located.

The tracing device is vintended for use with various kinds of universal cutting or welding machines, but is shown in the drawings as equipped with a bracket Ill (Fig. 1) for clamping itV to the front bar H of a conventional cutting machine of the folding parallelogram type. The bracket I0 is held in any set position along the bar II by a clamping screw I2.

The tracing device includes a housing I3 in which. certain parts of the tracing device are located, as hereinafter described, and below Which the power-driven traction wheel I4 projects. The housing I3 is mounted on the bracket I0 so as to be capable of vertical movement thereon and means are provided for moving the housing vertically to bring the traction wheel I 4 into contact with the drawing to be traced and for raising it away from the drawing. The particular means for movably mounting the housing on the bracket I0, and the particular means for raising and lowering the housing, form no part of the present invention and a detail description thereof is not necessary for a full understanding of the invention. It is sufficient to note that at the back of the housing I3 there are guide rollers I5 which move up and down along the two opposite lateral edge portions of a guide rail or plate I6 rigidly secured to the bracket IIJ. A chain I1 connected to the upper end of the housing I3 passes Varound an idler sprocket I8 at the upper end ofthe bracket I0 and wraps ground a sprocket (not shown) on a shaft I9, this sprocket be- The traction wheel I4 rotates on a horizontal shaft 2| (Fig. l) which is carried by the lowerend of a sleeve 22. This sleeve isr'otatableabout a, vertical axis in a ball bearing 231 at the upper part of the housing I3 (see Fig. 3 for a crosssectional showing of this ball bearing) and aI similar ball bearing 24 (Fig. 1) in the lower part of the housing. The vertical axis about which the sleeve 22 is rotatable, passes through the point of traction of the traction wheel i4. A gearl 215' is connected to one side yof the traction wheel I'4'` (see also Fig. 2) andmeshes with a driving Kpinion 26 mounted on a second horizontal shaft-2l carriedby th-e sleeve 22. The pinion 2li rotates witha `worm wheel 2 8, at the far side of the pinion-as viewed in Fig. l. This worm wheel meshes with a worm ,29 carried by the lower end of a. drive ene-ft 3c which' extends upward-1y through the sleeve 22'. The drive shaft is rotatably mounted in the `sleeve 22- bya ball bearing 3l at the upperend of the sleeve (Fig. 3) and a similar ball bearing 32 (Fig. 1) near the lower end of the sleeve,` the dri-ve shaftv being mounted in the bearings so thatr the axis ofthe driveshaft coincides with the axis of rotation ofthe sleeve 22.. It will beevident that rotation of the drive shaf-t causes the worm 29 to drive the traction wheel 'through the worm-Wheel 28, pinion 26 and gear 25 secured to the traction wheel.

The drive shaft 301s driven from an electric motor 33 supported on top of the housing. I3 (see also Fig. 2).` The motor is connected withthe driveushafti through reduction gearing te and a coupling 35v (Fig.-

The speed ofV the motorniay be control-led by an adjustable centrifugal speed con-trol governor 36 which may be adjusted by 4turning a knobi`3`l (Fig. 2) A-tachorneter 32 indicates" the speed at which the traction wheel-V 4 moves along thedravvingfor any given setting ofthe speed control governor of the motor.

The tracing device as thus far described is ofconventional type. Usually the sleeve, in whose lower end the traction wheel is mounted, is turned by hand-to steer the traction wheel to cause itto propel the tracing device along the outline of the drawing. However, in the tracing device s'hownin the drawings the steering of the traction wheel is effected automatically. The specific means' by which this is accomplished does not form part' ofl the present invention and therefore need not be described in detai1,. it being sumcient to-notethat a beamo f light represented by the line L (Figi l) from-a light source 39 is projected through the bottom ofH-the housing I3 onto the drawing" line and is reflected back into a photo- 'l/SC'C: Cll represented at im. Spcial drawings aiised having a wide lline, and the condition of edilibiiuhi of the traction wheel is obtained when tnojtrigrit spot of' l.iight oo the drawing is oneriair trie black une of' the drawing and oneljialf o'i the white paper adjacent the' line. 1f nie bright spot of iigiiil moves toward trie loi' k the amount of light received by the piio oeICtC" C'e'll is decreased and the tiatlri Wheel is turned about the axis of the sleeve 22 in a direction to move the bright spot of light back toward the edge of the line. Conversely, if the bright spot of light moves away from the black line of the drawing, the amount of light renected to the photo-electric cell increases and the traction. wheel is steered in the opposite direction to restore the: condition ofequilibrium. lThe turning of the traction wheel about the axis of the sleeve 22 is effected by an electric motor 4i which drives a worm 42 (Fig. 1) meshing with a worm wheelll secured to the sleeve 22. The motor is controlled by the photo-electric cell, and since the motor tui'hstliesleeve 22 in one direction or the other iti-accordance with the amount of light received by the photo-electric cell, it automatically steers" the tractionwhe'el and causes it to follow the-outline of the drawing.

In ord-er to insure satisfactory automatic steeringy of the traction wheel it is necessary to shield tl'i'e' drawingfrom excessive extraneous ligh'tth'at infgntberene'cted into the priotoeelectric cell arid' thereby produce unwanted changes in the o'rientation of the traction wheel. For this reason, the housing I3, which houses most of the parts of the' automatic' steering mechanism, is so made that it has a broad bottom area which is positoned close to the drawing when the tracer is in operation. The housing itself is thus used toshut on" from that portion of the drawing which is influencing the' phot0-el`ectric cell al1 or most of the' iight except that which is 'purposely projected onto the drawing" from the light source 39. This arrangement, however, has the" disadvantage that the housing so obscures the' traction wheel that the operator cannot s'ee which way itis turned or oriented when starting the tracing device'. To overcome this dihculty' there is secured to the upper end of the sleeve 22, above the housingv I3`, an indicator element which'is preferamy made viri the fornio`f a cylinder or' dr'rn 44' coaxially' ilitd n the Sleeve (-F'gs; 1 andA 3) The Cyl'- linder 44 is' enclosedV by a casing 45 in the' front portion of there is provided a window 4B (Figs.- I arid 2')r through which the Side Wall Of th "nder 44' may be seen. The cylinder 44 rotates with the sleeve 22l when th traction Wheel S s'td and the' surface 0fy the cylihde'r is thereby moved progressively by the window 4t.- Niiiheilalsandgraduations 41 are provided on the outside surface of the cylinder 44, and by viewing them through the window, the operator can alwaysV tell at a glance in what direction the traction wheel is headed.-

The numbering system used is preferably one which includes the numerals from I to I2 equally spaced around the cylinder in ascending order from lett to right, as shown in Fig.- 1, the numerals being s'o positioned on-the cylinder that when the traction wheel is oriented straight ahead the numeral I2 will appear in the window 46. Thus,y the numerals indicate to the operator the orientation ofthe traction wheel in muchthe same fashion that the direction of movement of an airplane or ship is designated by reference to thenuinerals of a clock. For example, if the numeral I2 appears at the window 46 the operator will' k'novv that the steering wheel is oriented straight ahead and that-the tracing device, when placed in operation, will move directly away from the" operator, i. e., toward the right as viewedin g. ,'1. If the numeral E is visible in the window the operator will know that the traction wheel will move the tracingv device toward him. I-f 'IS llilal 3 alifp i the' vvndw 46 the traction wheel is oriented in a direction to move the; tracing device toward the right, and the appearance of the numeral 9 in the window indicates a position of the traction wheel that will move the tracing device toward the left. Other numerals similarly indicate the various other angular positions of the traction wheel.

Anyother suitable type of markings on the indicator element or cylinder 44 may be employed which will inform the operator of the orientation of the traction wheel at any given time by the particular marking or markings visible through the Window at such time. For instance, a series oi arrows may be placed on the surface of the cylinder 44 in place of the numerals each of which, when visible through the window 4t, would inform the operator of the orientation of the traction wheel by the direction in which that arrow points.

It will now be seen that the indicator element is located at a position where it can be readily seen by the operator, and even though the traction wheel is obscured by the housing l 3, the operator can quickly determine the direction in which it is headed by noting which numeral or other marking is visible in the window. If the indicating device shows that the traction Wheel is not headed in the direction of that portion of the drawing line on which it is resting, the operator can make the necessary adjustment of the traction Wheel before the tracer is started.

The window 46 is made small enough to constitute a reference place by which the surface of the indicator cylinder or drum moves progressively when it turns with the sleeve 211. and which selects for the operators observation one .numeral or other marking that will inform him of the then position of the traction wheel, but some other type of reference place may be used. For instance, the reference place may be a stationary pointer or the like by which the numerals on the indicator cylinder move and which would sclectl for the operators observation one of the markings even if all or most of them were exposed to view. Various other changes may be made without departing from the invention as defined in the accompanying claims.

I claim:

1. In a tracing device having a traction wheel rotatable about a horizontal axle carried by the lower end of a sleeve that may be turned about a vertical axis to orient or steer the traction wheel, a motor-driven shaft extending through said sleeve and operatively connected to the traction Wheel to drive the same, automatic means for turning the sleeve to steer the traction wheel, and a housing through which said sleeve and shaft extend and which houses at least part of said automatic means for turning the sleeve, said housing having such size and location that it so obscures the traction wheel that its orientation cannot be readily observed by the operator,theim provement which comprises an indicator element connected to and movable with the upper portion of the sleeve above said housing where it may be readily seen by the operator to indicate the orientation of the traction Wheel at all times.

2. In a tracing device having a traction wheel rotatable about a horizontal axle carried by the lower end of a sleeve that may be turned about a vertical axis to orient or steer the traction wheel, a motor-driven shaft extending through said sleeve and operatively connected to the traction wheel to drive the same, means for automatically turning the sleeve about its vertical axis to steer 6 the traction wheel and cause it to follow an outline of a drawing or pattern, and a housing through which said sleeve and shaft extend and which houses at least part of said means, said housing being of such size and location as to so obscure the traction wheel that its orientation cannot be readily observed by the operator, the improvement which comprises a cylindrical mem.- ber coaxial with and secured to the upper portion of the sleeve above said housing Where it may be readily seen by the operator and where it moves progressively by a reference place when it turns with the sleeve, and markings on said cylindrical member to indicate the orientation of the traction wheel at any given time by the particular marking or markings which are at said reference place at such time.

3. A photo-electric tracer adapted to follow a pattern and comprising a housing that extends close to the pattern for shielding the pattern from extraneous light, a traction Wheel extending from the housing in a position to contact with the pattern at a region of the pattern shielded by the housing, an axle for the traction Wheel, a frame for turning the axle to steer the traction wheel, said frame being covered by the housing and rotatable with respect to the housing, an indicator element including a generally circular scale in the housing connected with the frame and rotatable With movements of the frame to steer the traction wheel, and a window in the housing through which the scale is visible for indicating the direction in which the traction wheel is in position to move.

4. A tracing device including a tracer wheel that runs on a support, a housing above and around the tracer wheel and located in position to shut off the view of the wheel from an operator of the tracing apparatus, an axle for the Wheel, a frame to which the axle is connected, means for turning the frame with respect to the tracer housing for changing the direction of travel of the tracer, a window in a part of the housing in position to be seen by an operator using the tracing device, an indicator in the housing immediately behind the window, legends on the indicator in position to become successively visible through the Window as the indicator turns, and connecting means for turning the indicator through angles similar to those turned by the frame to steer the tracer Wheel.

5. A tracing device including a wheel that runs on a surface, a frame connected with the wheel and rotatable about an axis substantially normal to said surface for steering the direction of travel of the wheel across said surface, a rotatable element that is connected with the frame and that rotates with said frame, and numerals around the periphery of the rotatable element, said numerals increasing in a counterclockwise direction around the entire angular extent of the rotatable element.

6. A tracing device including a tracer wheel that rolls Ion a surface, an axle for the Wheel, a

frame that holds the axle, a bearing in which the fra-me rotates to steer the tracer Wheel in any and changing directions across said surface, a direction indicator comprising an element connected with the frame so as to make angular movements similar to those of said frame when steering the tracer wheel, and angularly spaced numerals from one to twelve on the rotatable element with the numerals located so that they increase in a counterclockwise direction around said element and with the location of the respective numerals 2,468,802. 7f 8; so,i cornelaztedfwith thposton. of, thetracer, Wheel REFERENCES CITED axlethat the particulannumeral of. the direction indicator'` in front of an observer. corresponds to that of your designation :of aiclookface toward The following references are of record in the le of this patent:

which the tracer woul move if located at IcheL 5 UNITED STATES PATENTS cen-terni the clokface -and withrthe numeral six Number Name Date oi'the clockface nealresttheobserver. 1 166 680 Hanson l Jan 4., 1,916 1,901,254 Messer Mar. 141933 WALTER BEGEROW 2,336,581 Young Dec. 14, 1943; 2,349,954 Geibg May 30; 194% 2,349,955 Johnson May 30, 19.44:

Certificate of Correction Patent No. 2,468,802. May 3, 1949. WALTER BEGEROW It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 2, line 54, for the Word ground read around; column 7, line 4, claim 6, for that of your read that your;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the oase in the Patent Oce.

Signed and sealed this 1st day of November, A. D. 1949.

THOMAS F. MURPHY,

Assistant ommz'asz'oner of Patents. 

